Bentgrass (Agrostis stolonifera) is an important turf species in many areas of the world. The methods of biotechnology have been applied to bentgrass for improvement of the agronomic traits. One such agronomic trait is herbicide tolerance, in particular, tolerance to glyphosate herbicide. The control of weeds in bentgrass is particularly problematic. Bentgrass used on golf greens is especially sensitive to many herbicides that are normally used on other turfgrasses or on other areas of a golf course. Annual grasses, such as, crabgrass, foxtail, dallisgrass, and goosegrass must be controlled by use of a variety of herbicides including bensulide, dithiopyr, oxadiazon, fenoxaprop and prodiamine applied at specific rates, environmental conditions, and seasons by expert applicators in order to be effective. Annual and perennial broadleaf weeds may be controlled in bentgrass turf by applications of herbicides that include 2,4-D, MCPP, dicamba, and mixtures of these. Many grass and broadleaf herbicides cannot be used on bentgrass golf greens because of injury to the bentgrass, or they are not registered for use on bentgrass. There is a need for a glyphosate tolerant bentgrass to replace the use of these herbicides and to provide a method for effective grass and broadleaf weed control in bentgrass turf when glyphosate herbicide is applied.
N-phosphonomethylglycine, also known as glyphosate, is a well-known herbicide that has activity on a broad spectrum of plant species. Glyphosate is the active ingredient of Roundup® (Monsanto Co.), a safe herbicide having a desirably short half-life in the environment. When applied to a plant surface, glyphosate moves systemically through the plant. Glyphosate is phytotoxic due to its inhibition of the shikimic acid pathway, which provides a precursor for the synthesis of aromatic amino acids. Glyphosate inhibits the enzyme 5-enolpyruvyl-3-phosphoshikimate synthase (EPSPS) found in plants. Glyphosate tolerance can also be achieved by the expression of bacterial EPSPS variants and plant EPSPS variants that have lower affinity for glyphosate and therefore retain their catalytic activity in the presence of glyphosate (U.S. Pat. Nos. 5,633,435; 5,094,945, 4,535,060, and 6,040,497).
The expression of foreign genes in plants is known to be influenced by their chromosomal position, perhaps due to chromatin structure (e.g., heterochromatin) or the proximity of transcriptional regulation elements (e.g., enhancers) close to the integration site (Weising et al., Ann. Rev. Genet 22:421-477, 1988). For this reason, it is often necessary to screen a large number of events in order to identify an event characterized by optimal expression of a introduced gene of interest. For example, it has been observed in plants and in other organisms that there may be a wide variation in levels of expression of an introduced transgene among events. There may also be differences in spatial or temporal patterns of expression, for example, differences in the relative expression of a transgene in various plant tissues, that may not correspond to the patterns expected from transcriptional regulatory elements present in the introduced gene construct. For this reason, it is common to produce hundreds to thousands of different events and screen those events for a single event that has desired transgene expression levels and patterns for commercial purposes. An event that has desired levels or patterns of transgene expression is useful for introgressing the transgene into other genetic backgrounds by sexual crossing using conventional breeding methods. Progeny of such crosses maintain the transgene expression characteristics of the original transformant. This strategy is used to ensure reliable gene expression in a number of varieties that are well adapted to local growing conditions and market demands.
It would be advantageous to be able to detect the presence of a particular event in order to determine whether progeny of a sexual cross contain a transgene of interest. In addition, a method for detecting a particular event would be helpful for complying with regulations requiring the premarket approval and labeling of foods derived from recombinant crop plants, for example. It is possible to detect the presence of a transgene by any well known nucleic acid detection method such as the polymerase chain reaction (PCR) or DNA hybridization using nucleic acid probes. These detection methods generally focus on frequently used genetic elements, such as promoters, terminators, marker genes, etc. As a result, such methods may not be useful for discriminating between different events, particularly those produced using the same DNA construct unless the sequence of chromosomal DNA adjacent to the inserted DNA (“flanking DNA”) is known. An event-specific PCR assay is discussed, for example, by Windels et al. (Med. Fac. Landbouww, Univ. Gent 64/5b:459-462, 1999), who identified glyphosate tolerant soybean event 40-3-2 by PCR using a primer set spanning the junction between the insert and flanking DNA, specifically one primer that included sequence from the insert and a second primer that included sequence from flanking DNA. Event-specific DNA detection methods for a glyphosate tolerant corn event have also been described (US 20020013960 A1, herein incorporated by reference in it's entirety).
The present invention relates to a glyphosate herbicide tolerant bentgrass plant ASR-368 and to DNA compositions that comprise a transgene/genomic junction region contained in the genome of ASR-368 and to a method for detection of the transgene/genomic junction region in bentgrass plant ASR-368 and progeny thereof.